This invention is directed towards alkylene oxide adducts, especially polyether polyols, suitable for use in the preparation of flexible slabstock polyurethane foam and the manufacture of such alkylene oxide adducts from initiators comprising polymerized ethylene oxide.
When preparing polyurethane polymers, particularly flexible slabstock foam the nature of the polyol employed can be important for conferring the desired physical properties to the foamed product. Generally speaking, polyether polyols suitable for the preparation of slabstock foam will have an average functionality of from about 2 to about 4 and an equivalent weight of typically from about 800 to about 3000. Such polyether polyols can be prepared by reacting one or more alkylene oxide compounds with an initiator containing active hydrogen atoms in the presence of a basic, alkoxylation catalyst. Typically, the alkylene oxide compounds used usually include ethylene oxide and propylene oxide. Frequently an ethylene oxide content of at least 10 weight percent or more of the resulting polyether polyol is necessary if the product is to be commercially useful. The ethylene oxide content of the polyol serves a number of purposes including minimizing unsaturation and enhancing inherent surfactancy and thus ease of preparing good quality polyurethane foams. Physical properties of resulting foams including, for example, elongation properties are also improved by having an ethylene oxide content. A disadvantage of such a high ethylene oxide content is that it provides the polyol with an inherently high reactivity which consequently in manufacturing of foams permits only for narrow tin catalyst processing ranges.
Handling of, and use of alkylene oxide compounds in reactions to prepare polyether polyols requires care with respect to minimizing and preventing exposure of workers to these potentially harmful chemicals. In addition such alkylene oxide compounds by nature of their structure and oxygen content are often flammable liquids or gases, requiring further care and attention to minimize the risks of fire and/or explosion when being handled. These precautionary measures are required more so when handling ethylene oxide than other alkylene oxide compounds.
It is therefore desirable to find a means of producing polyether polyols which minimizes or eliminates the direct handling and use of ethylene oxide, and yet obtains polyether polyols which possess or confer desirable foam processing and/or foam properties
One possible way of avoiding the direct use of ethylene oxide is to use for example ethylene carbonate. When ethylene carbonate is contacted under the appropriate reaction and catalyst conditions with an active hydrogen-containing initiator it functions as ethylene oxide would do, allowing for the alkoxylation, ethoxylation, of the initiator. However, the type of catalyst and reaction conditions required are not the most favorable with respect to obtaining a polyether polyol of good quality for use in manufacturing flexible polyurethane foam. Polyether polyols so prepared can contain high levels of undesirable color, unsaturation and residues of catalyst not necessarily compatible with a polyurethane-forming reaction.
It is therefore desirable to find a means of providing a polyether polyol with an ethylene oxide content by a process which avoids the direct use of ethylene oxide as an alkoxylating agent and yet can provide products of acceptable quality which can be used to prepare polyurethane foams having commercially acceptable performance properties.